Fracture of the clavicle, i.e. the collarbone, is one of the most frequent fractures in humans (20 to 25% of all fractures in children and 5 to 15% of all fractures in adults). About 80% of clavicle fractures are shaft fractures. These fractures are usually treated conservatively by immobilisation in a sling for approximately 6 weeks. However, besides the considerably troublesome side-effects of the sling in some instances, e.g. disturbance of circulation/neurology as a result of plexus compression, both the functional and cosmetic long-term results in adults are unsatisfactory in some instances due to healing in the wrong position (“mal-union”) or pseudarthrosis (“non-union”) and prominent callus formation. Therefore, in the case of fractures of the shaft of the clavicle with an initially pronounced wrong position surgical stabilisation is increasingly performed. In this case, plate osteosynthesis is applied as “gold standard”. Alternatively, the clavicle fracture can be treated using an intramedullary nail. The advantages and disadvantages of the respective form of osteosynthesis are shown in the following table:
ImplantAdvantagesDisadvantagesPlate osteosynthesishigh primary stabilitylarge wound (at least 3 screws peranatomical resettingfracture → wound length > 6 cm)mostly possiblesubstantial devastation in the fractureregion and therefore disruption of thehealing of the fracture and risk ofpseudarthrosistherefore, removal of metal onlypossible after 18 months at the earliestextramedullary transfer of forceplate directly under the skin is generallyfound to be disturbing and painful inthe case of certain activities: e.g. whencarrying a backpack, playing anaccordion etc.removal of metal only possible underfull narcosis, in turn associated withcorrespondingly high operative traumaand reduced patient comfortIntramedullary naillittle operative trauma:less primary stability, in particular no(e.g. TEN or Thalon)small incision medialcompression onto fractureclavicle, additionalrisk of secondary dislocation andincision over fracturepseudarthrosis (“non-union”) andregion for openimplant migration (life-threatening inresetting, if necessarysome instances!)removal of metal generally only possibleunder full narcosis, in turn associatedwith correspondingly high operativetrauma and reduced patient comfort
In order to obtain a high primary stability by way of a minimally invasive access while achieving vascularisation in the fracture region and, moreover, to also allow metal to be removed under local anaesthesia, a completely new osteosynthesis principle is to be developed that can be applied in particular in the case of a clavicle fracture, but also in principle to other long bones.
There are already advanced approaches in the use of non-rigid connecting elements for the treatment of joint injuries.
A simplified joint-bridging implant in the case of bone fractures close to the joint, but in particular in the case of joint dislocations, is illustrated in DE 36 30 138 A1. In DE 36 30 138 A1 steel cords are used in this case to allow an elastic connection of joint parts. Two anchor parts are provided, one of which is respectively secured to the bone or joint part and both anchor parts are articulated to one another, wherein the connection is formed by at least one cord. However, DE 36 30 138 A1 is merely aimed at a flexible connection in the case of joint fractures, and a rigid connection of a broken long bone is not disclosed. The implant is not resorbable and not for implantation in a minimally invasive manner.
For a joint-bridging implant DE 196 18 552 A1 proposes to drive a bone segment by a tensile force generated in a cord by flexion of the healthy bone articulated in the joint and caused to act directly or indirectly on the segment by said cord in an intermedullary arrangement by means of an intramedullary nail in order to transport the segment autoinductively using a complete implanted device to bridge a bone defect on a long bone. Transverse pins are necessary to stabilise the intramedullary system. However, the set problem and the proposed approach for solution are likewise not readily transferable to the case of bones broken with clean fractures. Moreover, the implant is not resorbable and not for implantation in a minimally invasive manner.
DE 1 852 874 U shows an implant for connecting two parts of a broken long bone, wherein the implant is formed by a shaped piece that is intended for insertion into the medullary cavity of a broken long bone. The shaped piece has a through-opening with a constant inside diameter that extends through the entire shaped piece. The implant must function without tension, as a result of which no fracture compression is achieved. Moreover, transverse pins are required to stabilise the intramedullary system. Furthermore, DE 1 852 874 U does not disclose a resorbable material or a minimally invasive implantation.
U.S. Pat. No. 6,045,551 discloses an implant running transversely to the bone axis for the tension-resistant connection of two parts of a broken long bone, wherein the implant has two anchor parts, a cord and a shaped piece, wherein the anchor parts can be secured to the one cord, wherein the shaped piece has a through-opening, through which the cord is guided so that the shaped piece extends around the cord between two anchor parts. Since a plurality of cord anchors are required, the implant is not implanted in a minimally invasive manner and no simplification of the operation or reduction in operating time is achieved.
DE 824 377 relates to a non-resorbable device for pulling together the fractured ends of a broken long bone by means of a pulling member, which is to be inserted at a spacing from the fracture site and has an anchor that lodges against the bone wall with a pull. However, DE 824 377 does not disclose a tubular implant that could prevent a translatory dislocation tendency of the bone ends.
EP 0 428 985 A1 describes an intramedullary nail that can be secured in a long bone by means of a wire loop, wherein the primary aim of EP 0 428 985 A1 is simplified distal locking. However, transverse pins must be inserted both in the proximal and the distal end of the fractured bone for stabilisation of the intramedullary system, and these, like the intramedullary nail itself, are not resorbable.
A resorbable osteosynthetic element is described in FR 2 721 818. It consists of an anchor, an elastic cord, a tensioning device and a fastening. One end of the cord is secured to the anchor, while the other is connected to the tensioning device and the fastening after it has been pulled through-holes that have been drilled into the two bone parts. The anchor is secured to the surface of one bone fragment, while the tensioning device and fastening are secured to the surface of the other bone fragment. However, FR 2 721 818 does not disclose a shaped piece that can be inserted into the medullary cavity of a broken long bone to ensure a secure fixture of the cord.
Further bio-resorbable systems for insertion in bones are described in U.S. Pat. No. 6,096,060, which describes an anchor system for securing soft tissue to the bone, and in U.S. Pat. No. 5,470,334, which describes a bone fixing screw. However, neither system is suitable for the treatment of clavicle fractures.
It is therefore desirable to have an implant available that allows the fractured pieces of a long bone to be stabilised by an implant with less expenditure than previously.
It is additionally desirable to have an implant available that allows the removal of the implant after biological union to be substantially simplified.
An aim is to have an operating technique available that allows a surgical intervention for implanting and removing an implant to be simplified.
In addition, as in all surgical procedures, the aim is to achieve a gentle operation with only slight blood loss and small wound surface, while still providing a stable fracture treatment.